Modified lubricating oil



Patented May 5, 1942 11 OFFICE MODIFIED LUBBICATING OIL Ulric n. Bray, Palos Verdes Estates, Calif., a-

: signor to Union Oil Company of California, Los Angeles, Calif., a corporation of California No Drawing. Application September 22, 1939, Serial N0. 296,093

33Claims. (01. 252-39) This invention relates to mineral lubricating oils which have been modified by the addition of constituents to impart to them special characteristics especially adapting them to severe service uses as in Diesel engines, high output aviation engines and the like.

Primarily, the object of the invention is to produce lubricating oils for such severe service uses which will avoid the deposit of lacquer and varnish-like materials frequently found upon pistons, and also to .overcome carbon deposits behind the rings, and further to prevent bearing corrosion where corrosion-sensitive bearings of the copper-lead and cadmium-silver type are employed.

With respect to requirements for a desirable non-corrosive Diesel engine oil, my investigations have established that such (1) a non-corrosive oil must be either neutral or not sufllciently acidic at any time to cause bearing corrosion, and (2) the'soap employed in the non-corrosive oil must be adequately soluble in a neutralor alkaline solution to obtain the benefits previously found to exist in soap-compounded lubricating oils. I have further discovered that a soap-compounded oil, containing for example calcium soap of a suitable high molecular weight carboiwlic acid, which is neutral or slightly alkaline when placed in the engine, soon develops acidity during operation up to the point where the organic acids formed attack cadmium-silver or copper-lead bearings employed in the engine. While definite proof is diflicult to obtain, I believe, as a result of my experimental observations, that the corrosive acidity developing during use of the oil is a result of oxidation of the base oil, said oxidation probably being catalyzed by the metallic constituent of the soap used in compounding the oil. I have, therefore, concluded that further requirements for a satisfactory non-corrosive oil are (3) that the oil should contain an oxidation inhibitor or poisoner for the metallic catalyst to retard or prevent catalytic oxidation of the oil resulting in corrosive acids, and (4) that the oil should contain an oil-soluble neutralizing agent which will present a source of reserve alkalinity. capable of neutralizing corrosive acids which may develop in spite of the presence of the oxidation inhibitor.

Thus, a satisfactory non-corrosive mineral lubricating oil (1) should be neutral or substantially so, (2) should contain a soap soluble in the oil under these neutral conditions, (3) should also contain an oxidation inhibitor or deactivator for metal catalyst present, and (4) should contain a source of reserve alkalinity. Also (5) the oil should contain a film strength agent either incorporated inone of the foregoingingredients or separately added as in the form of a high molecular weight organic compound containing chlorine, phosphorus or sulfur. A single material such as the calcium salt of an alkyl hydroxy phenyl thio ether, may perform each of the last three functions.

Heretofore, I have produced Diesel engine oils containing soaps of such metals as alkaline earth metals, particularly calciumjformed with modified fatty acids and synthetic petroleum acids produced 'by the oxidation of petroleum fractions, these soaps being employed for their detergent effect in preventing the accumulation and deposition of carbon and resinous or varnish-like materials, and to some extent removing such materials when once deposited. As above indicated,

.acid formation in the engine apparently is catalyzed by the metal constituent of the soap, inasmuch as the oils themselves when used alone do not develop such corrosive conditions, at least to any material extent. I have discovered that this difilculty may be in part overcome by using soap-forming metals which ofier the least catalytic effect. In general, the alkaline earth metals appear definitely superior. Of these, barium appears to be the best; calcium is very desirable and for practical uses probably is generally preferable; magnesium, while usable, produces appreciable catalytic action. In addition to employing a metal in the soap presenting a minimum of catalytic action, I also add to the oil a second addition agent which possesses an alkalizing efiiect, or as I have elected to call it reserve alkalinity, that is a material which will readily react with the strong oxidation acids formed to neutralize said acids and release in the oil either a very weak acidic material or some other nonobjectionable byproduct, even to the extent of a volatile byproduct. Such agent could have, and preferably would have, some inhibiting effect apart from neutralization. I may also employ a third constituent which willact positively to poison the catalytic eifect of the metal, for example, phosphorus or sulfur in chemical combination. Conveniently, I may employ a single chemical compound containing both the alkalizing and catalyst-poisoning constituents. Thus, I may use a calcium salt of an organic material containing sulfur such as hydroxy phenyl thio ether, or a kindred oil-soluble organo-metallic compound, that is a metal-bearing organic compound. Obviously, the materials mentioned must materials, either by poisoning the catalyst and 1 preventing the formation of such'acids, or by neutralizing such acids as they are formed thereby to yield harmless byproducts, or by both poisoning the catalyst metal and neutralizing strong corrosive products formed, or otherwise inhibiting corrosive conditions. The mineral lubricating oil employed may'bea California or naphthenic type oil which ordinarily contains about 0.5% naturally combined sulfur, but may contain as little as 0.15% of such sulfur. Higher sulfur content oils such as Santa Maria Valley (California) oils containing up to 4% or even 5%, for example 2.75% of such sulfur, are sometimes very desirable. This sulfur also tends to inhibit bearing corrosion and the formation of the acid conditions causing it, as elsewhere herein indicated. With soaps of adequate oil-solubility, as in the case of the calcium soap of acids produced by oxidation of highly refined dewaxed paraflinic oils, the base oil may be a well refined parafilnic type oil.

In previous applications I have disclosed the desirability of increasing the film strength of soap-compounded Diesel engine oils beyond the film strength imparted ordinarily by soaps of high vention resides further in the inclusion in some such appropriate form of a film strength agent such as chlorine, sulfur or phosphorus adequate to impart the said required film strength of about 15 pounds on the 'Iimken machine. This agent, sulfur for example, may appear in the oil or one of the compounds used for other purposes such as the mentioned sulfur-bearing phenolic material for controlling the catalytic action, or otherwise as may seem necessary or desirable.

According to a preferred form of the invention, I employ calcium soap of the synthetic acids produced by the oxidation of petroleum fractions. Preferably, these synthetic acids are produced by oxidizing very highly paraflinic lubricating oils, such as have been produced by the severe solvent extraction of dewaxed lubricating stocks, as by means of liquid sulfur dioxide-benzol mixtures, phenol, chloraniline, dichlorethylether, and the like. The oxidation-acids so produced are highly oil-soluble, and likewise their soaps are highly oil-soluble. These soaps are employed in the lubricating oil in ranges between about 0.5% and 1.5%, the optimum being apparently from 0.7% to about 1% or 1.1%. As to these soaps, appreciably higher percentages perform little additional function and merely increase the cost. In addition to calcium soap, I may also use the Mental earth metal soap. namely magnesium soap. is apparently somewhat less desirable.

As a preferred poisoning and alkalizing agent possessing said required "reserve alkalinity, I. have used with the above soap about 0.5%, or

between about 0.3% and 1%, of the calcium salt of hydroxy phenyl thio ethers containing aliphatic side chains such as butyl, amyl and the like. These salts also are adequately oil-soluble.

Therefore, the invention further resides in the employment of between about 0.5% and 1.5% of the calcium soap or indicated equivalent alkaline earth metal soap of the synthetic petroleum acids produced by the oxidation of petroleum fractions, preferably of highly paraflinic mineral lubricating oils, together with a small percentage in the order of 0.5% of an oil-soluble organometallic compound containing a catalyst poisoning and/or inhibiting constituent agent such as phosphorus or sulfur and a constituent combined therewith by means of which the compound may present reserve alkalinity by acting to neutralize the relatively strong objectionable corrosive organic acids formed during engine operation. As one preferred organo-metallic compound, the invention includes the calcium salt of hydroxy phenyl thio ethers, especially where they contain aliphatic side chains of sufiicient length to impart good oil-solubility to the salts, such chains being in the order of butyl, amyl or heavier aliphatic radicals. These compounds may be viewed from the standpoint of inhibitors of corrosion, or inhibitors of development of corrosive conditions, or catalyst poisoners.

In addition to the preferred calcium and barium soaps of the synthetic petroleum acids from the oxidation of highly refined highly parafiinic petroleum lubricating oils, I may also employ soaps of acids from the oxidation of other pc- 0 troleum fractions as previously indicated, and

likewise, I may employ other adequately oil-soluble alkaline earth metal soaps of organic acids, includingchlorinated stearic acids such as those containing chlorine roughly corresponding to the dichloro acids, or mixtures of mono and dichloro stearic acids, and other chlorinated high molecular weight fatty acids whose soaps have adequate oil-solubility. Similarly, calcium soaps of hydrogenated abietic acids may be employed-using if necessary a common solvent to promote-adequate oil-solubility. Even calcium soaps of unmodified higher molecular weight fatty acids may be employed as detergents, at least as part of the soap, where a common solvent is added or the organometallic neutralizing compound has sufiicient solubilizing effect upon the soap, as is true to some extent with calciumvsalts of alkyl hydroxy phenyl thio ethers mentioned. In the case of fatty acid soaps or modified fatty acid soaps, the soap ranges are approximately the same as with the preferred soaps above indicated, the upper range of 1.5% being a practical limit for the further reason that materially greater amounts tend to increase the viscosity of the original oil objechighly desirable barium soap. The other alkaline tionably, even where the organo-metallic neutralizing compound possesses some common solvent characteristics for the soap as do the calcium salts of the phenol thio ethers above mentioned. In any case. where a tendency to gel arises, as where a modified or unmodified or mixed fatty acid soap is used with inhibitor salts of higher phenolic materials, or in similar combinations, any suitable high boiling common solvent may be added in appropriate amount. High boiling alcohol-ethers are good examples especially those having boiling points above about 200 C. From 0.1% to 0.5% will ordinarily be sufiicient, for example 0.15% of triethylene glycol, which also may be used in other small proportions within the limits of its oil-solubility in the presence of said soaps. Other suitable materials are represented by diethylene glycol, tetra-ethylene glycol, ptertiary-butyl phenoxy ethanol, diethylene glycol monoethylether, diethylene glycol monobutyl ether, ethylene glycol monophenyl ether, and the like. These common solvents act to insure retention of the soap in the oil and to overcome gelation of the soap solution in the event of the entrance of water.

Where the catalyst poisoner, which may also be called an anti-oxidant, is a separate compound from the organo-metallic neutralizer, I may employ as such a catalyst poisoner or anti-oxidant materials containing phosphorus or sulfur such as triphenyl phosphite, tri-tertiary amyl phenyl phosphite, dibenzyl' disulfide and the like, these materials containing organic rings or equivalent radicals adapted to impart solubility of the compound in the mineral oil. When such anti-oxidants are used, the neutralizer may be any oilsoluble organo-metallic compound of alkaline nature, where the salt will react or combine with the stronger acids formed during operation to keep the oil neutral and thereby act as a bufiering agent. Such neutralizing agents are represented by calcium diethyl and calcium tetraethyl; the complex calcium salt of ammonia (azide) wherein another of the hydrogens is replaced with a hydrocarbon chain to render the material oilsoluble; the calcium reaction products with high molecular weight mercaptains (calcium mercaptidesRSCa); the calcium salts of condensation products of phenol and formaldehyde, the calcium having been introduced into the condensation product before the OH conversion was complete, thereby replacing part of the OH groups with calcium and thus producing an oil-soluble calcium compound. Similar barium salts may be employed, and, while not so desirable, similar magnesium salts also sometimes may be employed. To illustrate and determine the neutralizing eflect of the oil-soluble calcium compounds of the type shown above, 1.5% oleic acid was added to an ordinary mineral lubricating oil giving an acid-number of 2.86. To this blend was next added 3% of a 16% solution of the calcium salt of mixed alkylated hydroxy phenyl thio ethers, giving the blend a sulfated ash content of 0.15%. After this addition, the blend was tested and found to have an acid number of 1.95, showing that the added calcium compound had a neutralizing effect equivalent to 0.91 acid number. Smaller or larger additions of the calcium compound would have correspondingly smaller or larger neutralizing efiect. Thus, it is possible to add an appropriate quantity of alkalizing agent to offset any predetermined amount of acidity.

Suitable methods of producing the synthetic petroleum acids by oxidation, are sufliciently well known and need not be here described. Similarly, the production of the oil-soluble calcium or magnesium organic anti-oxidant compounds mentioned will in general be understood by those skilled in the art. A specific alkyl hydroxy phenyl thio ether mentioned is described in the Mikeska et a1. Patent No. 2,139,766 and other similar compounds and their methods of preparation are given in Mikeska et' a1. Patent 2,139,321. The calcium salt thereof may be conveniently obtained by first adding the starting material to an ture is then commingled with hydrated calcium oxide and a small proportion of water, followed by heating to about 300 F. with agitation for a time to insure neutralization. The resultant mixture is filtered to remove solids such as excess calcium oxide. The ash (calcium content) has been increased when desired by first heating only to about 200 F. to 210 F. for a time to insure complete admixture and partial neutralization, the mixture being then cooled toy 150 F. to 170 F., and a small quantity in theorder of about 3% of 95% alcohol being added, and the temperature of the mix being then raised to the previously mentioned temperature of 300 F. Another method employed has been to neutralize the alkyl phenol sulfide with sodium hydroxide, and

then by metathesis with calcium chloride or the like convert the sodium salt to the calcium salt. A starting material believed to be kindred to that of the Mikeska et al. Patent 2,139,766 is at present obtainable on the market under the trade name Paranox which is available from the Standard Oil Development Company. This material is furnished in about 80% of a lubricating oil mixture; to which an equal quantity of the aforementioned suitable lubricating oil is added preparatory to conversion. The above described neutralization to produce these calcium salts thereof is more or less easily accomplished due to the fact that the pure phenolic "material has been found to have an acid number of about 98. The other alkaline earth metal salts may be produced in similar manner.

These salts are readily soluble in lubricating oils in the required proportions and yield alkaline rather than acid solutions. Representative salts thus produced appear to have the following structural formulas:

Another calcium salt which has e n prepared is the salt of di-p-tert-amyl diphsnyl sulfide, this salt apparently having the following formula:

C......... Q. .:H CH.

and possibly also a structure having two doublering muclei Joined to the calcium corresponding with the second structural formula given above. S in these formulas in general represents one sulfur atom but in some instances may also represent two or more sulfur atoms. 7

The percentage of these inhibiting salts is, as above indicated, such as to eilectually control or overcome the development of corrosive conditions in the oil during engine use so as to avoid attacking highly corrosion-sensitive bearings such as copper-lead bearings. Where effective inhibitors are not employed, it has been found that the lead is too easily leached out from the copper at the bearing surface so as to leave a weakened, porous or spongy copper bearing. According to the present invention, the inhibitor introduced overcomes such action. A suitable percentage of salts containing bothan alkalizing agent and a poisoner such as phosphorus or sulfur, has been found to be about 0.5% or in the order of from about 0.2% or 0.3% to possibly as high as one percent (1%) where. the calcium salt of the above de-- scribed alkylated phenol thio ether was employed. Increased amounts such as 1.5% of such salt do not appear to offer any objection, but they do not appear to ofier any benefit except where the soap employed results in or catalyzes a greater percentage of corrosive acid constituents than in the case of the calcium soaps of the synthetic petroieum acids produced by oxidation. These amounts of the allralizing inhibitor are, of course, based upon the previously indicated amounts of soap in the order of from about 0.5% to about 1.5%. In general, the alkalizing value of the calcium compound added should be equivalent to at least 0.8 acid number in order to keep the acid number of the crankcase oil below the point of rapid corrosion of alloy bearings.

With respect to what has been said about the amount of catalytic soap or the amount of catalytic metal present in the soap, tests have indicated that a maximum amount of corrosive materials is produced in the oil when the mrcentage of soap based on the total oil content is about 0.3% to 0.4%. From zero percent soap up to perhaps 0.3% soap, the curve of the catalytic action rises rapidly as determined by acid number developed. From about 0.4% soap the curve drops and from about 0.6% soap out through 1.0% soap the curve is substantially straight. The small percentages of soap of below 0.3% are too small to produce any valuable effect even apart from the question of development of corrosive materials. From about 0.5% upward the efl'ect of increasing the soap-content is favorable. Concentrations between 0.7% and 1.0% or 1.1% of soap are adequate from the standpoints of both development of acidity and engine cleanliness. The optimum range appears to begin at about 0.7% soap and to extend to the upper practical limit of about 1.1% or 1.2% soap. Above about 1.1% of a calcium soap of synthetic petroleum acids produced by oxidation, especially of highly paraiiinic lubricating oil fractions, no great improvement in the oil is found, although up to about 1.5% may be used without any apparent objection. In the case of some oil-soluble fatty acid soaps, such as a calcium chiorostearate or the like, it may be desirable to increase the soap content up to about 1.3%. Above this upper limit, there appears to be no practical value, and in the case of some soaps there will develop the practical objection that the viscosity of the original oil will be appreciably and, therefore, objectionably increased.

It is to be noted that the metal in the inhibiting or alkalizing salt does not appear to act catalytically, and that when the calcium thereof combines with the strong oxidation acids produced in the engine, it apparently is then so closely bound that it can exert no catalytic efiect, or for some other reason exerts no catalytic effect. Thus,

dearest it is only the metal in the soap that needs to be inhibited.

It. is to be understood that the soap content, which is employed as a measure of the catalytic activity of the metal constituent, refers to soaps of moderately high molecular weight saponifiable organic acids such as those containing from perhaps 12 to 14 carbons per molecule up to perhaps 25 or 30 carbons per molecule, thereby including materials such as stcaric acid and other fatty acids including chlorinated fatty acids, and the synthetic petroleum acids produced by the oxidation of petroleum fractions, especially the dewaxed highly refined highly parafllnic lubricating oil fraction mentioned. As the molecular weight of the acid might be substantially changed, the curve might shift slightly. However, the optimum range generally indicated as being between about 0.6% or 0.7% and about 1.0% to 1.1%, would not be appreciablychanged.

With respect to the saponifiable organic acids used for production of the various types of soaps mentioned, these will ordinarily be high molecular weight materials containing more than about 10 carbon atoms per molecule. This will include the various saponifiable fatty acids employed such as stearic acid, palmitic acid and others of this series and a corresponding chlorinated or otherwise halogenated fatty acid. Likewise, the preferred synthetic petroleum acids from oxida-- tion of petroleum fractions mentioned will possess carbon atoms per molecule within the range stated,

It is to be understood, as has been previously indicated, that while calcium soaps have been referred to throughout in connection with the examples,this has beenldo'ne because calcium now appears to represent themost practical soapforming metal. for effectiveness from the standpoint of avoiding catalytic eil'ect, barium is preferable. Also, while magnesium soaps may be used in some instances, they are not preferred to the calcium soaps because the magnesium appears to possess somewhat greater catalytic activity than does the calcium.

With respect to the salts of the inhibiting materials mentioned, such as salts of the mixed alkyl hydroxy phenyl thio ethers disclosed, again calcium seems to be a preferred salt-forming metal, although it does not appear that the metal in these salts possesses any particular catalytic effect for the reasons heretofore given. But apparently other metals such as barium and magnesium may be substituted for calcium in the preparation ofsuch salts. Again in using materials for the formation of these neutralizing or oxidation-inhibiting salts, other suitable constituents may be substituted for the sulfur therein such as prosphorus or in some instances selenium. Thus, instead of having the salts of the thio ethers above mentioned, salts of phosphorus ethers or salts of selenium ethers might be used.

With respect to the base mineral lubricating oil to which the above described soaps and salts are to be added, I'may use any appropriate mineral lubricating oil. Naphthenic base or western type mineral lubricating oils are suitable inasmuch as these oils in themselves possess some native solvent properties for resinous and varnish-like materials which tend to form in the engines. These oils usually also contain naturallyoccurring inhibitors such as sulfur. California S. A. E. 30 lubricating oils having vis- However, it also appears that I I have used higher.

2,281,024 i coslties of about560 to too seconds Saybolt mudescribed, 1. e.

versal at 100 F. and a viscosity index of about 15, and containing about 0.5% sulfur. Another desirable oil is one containing a largerproportion of naturally-occurring inhibitors. SuchQan oil is thenaphthenic type lubricating oil obtained from Santa, Maria Valley (California) stock which is high,

in natural sulfur content. Kindred oils are spindletop (Texas) and the Smackover (Arkansas) oils. Such oils are to be thoroughly acid treated whereby loosely combined or objectionable sulfur forms are removed. appreciable percentages of the desired naturally-occurring sulfur materials nevertheless remaining. For example, a typical Santa Maria Valley lubricating oil will contain about 2.5% to 3% and sometimes possess a film strength in excess of-15 pounds as measured by the Timken lubricants testingand liners as determined by actual operation,:.

California s. A.\ lubricating oil (ref red to. as 260 oil) having a viscosity of about 6 seconds Say'bolt Universal at 100- n, a viscosity index of about 15, and containing about 0.5% combined sulfur naturally \occurring in theoil. This blend possessed an A. P. I. gravity at 60'F. ofl9.7. ,It was alkallna. had a sulfate ash of 0.27%, and had approxi-y mately thesame viscosity asthe original oil.

The above oil was submitted to a series attests to determine its oxidation characteristics. For

this purpose the oil was used in the crankcase of a Diesel engine equipped with coDPBfi-lead Since it is' desirable that the product sucha high sulfur-bearing naphthenic oil as above mentioned will meet this requirement because of thepresence of the chemically-combined sulfur naturally occurring in the oil.

Therefore a desirable complete product may consist of Santa Maria Valley lubricating oil containing calcium soaps of synthetic petroleum acids from the oxidation of parailinic fractions as herein indicated, and calcium salt of aryl hydroxythio ethers as herein indicated. Further with respect to the base oil, it isalso possible to employ eastern oils or other parafllnic type oils with the above soap and salt. These various oils may have their film strength improved by small percentages in the order of 0.5% to perhaps 1.5% of chlorinated materials such as ch10:

rinated naphthalene or chlorinated diphenyl.

Smallamcuntsofphosphorouscompounds may be employed for similar purposes, as well as for catalyst poisoningpur'poses, such as tri-cresyl phosphate, tri phenyl phosphite, tri-cresyl thiophosphate and other organic phosphorous compounds appropriate, for the purpose. Where soaps are employed which require common solvents to insure adequate retention in the oil, salts such as the calcium salt of the alkyl hydroxy phenyl thio ethers mentioned will exert some such influence. Otherwise, orwhere such influence is not sumcient,a common solvent may be used as previous- 1y indicated, for example from 0.l% to 0.15% of triethylene glycol or triethanolamine; or other means may be employed for overcoming gelforrning. tendencies .when present.

So far as the incorporation of sulfur,-phosphorlls and, a halogen, asi'or the purpose of imparting film strength, is concerned, this may also be accomplished. by incorporating -the sulfur, phosphorus or halogen directly into the saponifiableorganic acid constituent of the soap by chemical combination. Preferably, this will be done prior to the saponification of the acids. This applies both to the preferred synthetic acids from the oxidation of petroleum fractions, and to fatty. acids such as stearic acid, oleic acid, linoleic acid, palmitic acid, coconut fatty acids and other usable fatty acids.

A, specific product which I have made and used contained. the following: 0.75% calcium soap of ;the.-syntheticacidls produced by the oxidation of 'S. 10 grade highly paraffinic lubricating.oil.,.iraction;- 0.50% calcium salt of bearings with a crankcase temperature 01 210? F. to' 215 F. To insure such temperatures the engine'was housed and the? air in the housing superheated to about 165 F. The engine was a 4% inch engine operated at 1400 R. P. M. under a continuous high load of B. M. E. P. (brake mean eflective pressure). Under these conditions, an ordinary soap-compounded oil, such as an oil containing calcium phenyl stearate, willyield an acid number of 0.8 in 15 hours,and corheavy. With the oil composition abovedescribed containing 0.75% of the calcium soap of the oxidation acids from highly parailinic lubricating oil fractions and 0.5% of the calcium salt ofthe mixed alkyl phenol thio ethers mentioned, the acid numbers developed as follows:

At 25 hours of engine operationl'he oil was alkaline 1 4 At 50 hours of engine operation-Slightly alkaline to neutral e At 75 hours of'engine operation-Neutral At 100 hours of engine operation-0.30 acid number At l20'hours of engine operation- 0.60 acid num- 0 her Corrosionof cadmium-silver bearings occurs at an I 7 acid number somewhat above 0.6, such as 0.66.

Since an engine is ordinarily drained after use under severe conditions such as might approximate the above conditions, it is apparent that this oil possesses a high factor of safety.

Another product which I have prepared was a solvent-treated highly parafllnic mineral lubrieating oil of S. A. E. 20 grade which contained 1.0% of the calcium soap of the synthetic acids produced by oxidation. of highly parafllnic lubrieating oil fractions as above described and corresponding with the parafllnic oil employed in preparing thelubricant, and 0.5% of the calcium salt'ot the same mixed alkyl phenolthio ethers above described, i. e. from Paranox. This 011 alsoppossesses highly. valuable properties, and demonstratesthe, fact .that a highly valuable Dieselengineoil can be 'made. also from a highly paraflinic type mineral lubricating oil by reason of the fact that the soaps of the synthetic acids from the oxidation of. such oils are highlycompatible with these oils,-

distinguishedxfrom \from Paranox; 98.75% or a I it naphthenic type mineral rosion of the cadmium-silverv bearings will be for 60ho'urs, or aftera shorter use when operated II l 6 sticking is obtained, and in addition the tend cies of the oil to development of corrosive conditions are so inhibited and such acidity as may develop'is so counteracted or neutralized that the 1 oil, even under the severe test conditions such as temperatures of 300 F., does not develop an ob- Jectionable degree of acidity short of about 100 hours. While it is true that after a longer in terval of time the oxidation curve begins to run up rapidly, nevertheless that condition is'not reached until long after the, oil has passed its normal period of usefulness. Also, as previously gineunder severe conditions of 210 F. to 215 1".

, crankcase test temperature, an acid number 01" 0.6 was not reached until 120 hours. Since a normal use may be set at'about 60 hours, it is noted, where 260 oil,containing 0.75% of .the I calcium synthetic acid soaps was run in an en duced by the oxidation of highly refined, highly obvious that all the present oils meet every requirement, including resistance to oxidation and development of corrosive conditions, together with adequate detergent properties to impart adequate piston cleanliness and freedom irom ring sticking.

I These disclosures illustrate the nature oi the invention disclosed, but it is to be understood that I small proportion of an alkaline earth metal soap of a saponiflable organic acid to overcome the deposit of resinous and varnish-like materials in severe service internal combustion engines. and a relatively small 'quantity 01 an oil-soluble paramnic petroleum lubricating fractions, and between about 0.3% and 1.5% of an alkaline earth metal organic compound oi a phenol thicether capable of reacting with products formed in the engine corrosive to, highly corrosion-sensitive bearings.

7. A lubricating oil according to claim 6 wherein the organic compound of alkaline nature is an alkyiated thioether phenolate.

8. An oilaccording to claim 6 containing a constituent capable of poisoning the catalytic eflect oi' the soap toward the development of said corrosive products of the class consisting of phosphorus, sulfur and selenium.

9. A mineral lubricating oil containing between about 0.6% and 1.5% of an oil-soluble alkaline earth metal soap of a saponiflable organic acid,

alkaline earth metal compound of a thio-pheiiolic I derivative to overcome corrosive conditions developed in the oil. the added constituents not materially increasing the viscosity of the original lubricating oil. I

2. A mineral lubricating oil containing in solution a small percentage 01' an oil-soluble alkaline tion having the form oI an alkylated metal bearing phenate compound of an alkaline earth metal adapted to react with highly corrosive materials developed in engine operation, the'oil also containing a constituent capable 1o! poisoning the eflect of the soap to catalyze development or corrosive materials, the viscosity. of the .oil product not being materially greater 'than that of the original base oil. I

3. A mineral lubricating o for severe service internal combustion engines ontaining an oilsoluble alkaline earth metal soap of saponinable organic acids in amount between about 0.6% and about 1.5%, and between about 0.3% and about 1% of an oil-soluble alkaline earth metal compound of a thiophenolic derivative in combination with a constituent for poisoning the catalytic eflect of the soap. the metal-bearing organic sulfur compound being adapted to oflset strongly corrosive conditions produced in an en- .gine during operation.

' 4. A mineral lubricating oil for severe service internal combustionengines containing an oil- -soluble alkaline earth metal soap of synthetic acids produced by the oxidation of petroleum fractions in quantity to overcome the depomtion soap and between about 0.3% and 1.5% or an oilsoluble alkaline earth metal organic compound in the form or a thiophenate possessing neutralizing properties to control the production of materials corrosive to highly corrosion-sensitive bearings. I

,10. A mineral lubricating oil for severe service internal combustion engines containing between about 0.6% and 1.5% of an oil-soluble alkaline earth metal soap 0! a saponiiiable organic acid. and between about 0.2% and 1.5% of analkaline earth metal salt cf-analkylated hydroxy phenyl thio ether.

11. A mineral lubricating oil according to claim 10 wherein the soap is an alkaline earth metal m of a high molecular weight modified fatty 12. 'A mineral lubricating 011 according to .claim 10 wherein the soap is from a class consisting oi calcium, barium and magnesium soaps of synthetic petroleum acids produced from the oxidation oi hig refined, highly paraflinic mineral lubricating fractions.

13. A lubricating oil according to claim 1 wherein the soap is a calcium, barium or magnesium soap. 1

14. A' lubricating oil according to claim 4 wherein the mineral lubricating oil is a naphthenic base oii containing naturally-occurring combined sultur. 15. A lubricating oil according to claim 9 wherein the mineral lubricating oil is a naphthenicjase oil containing naturally-occurring combined sulfur.

16. A lubricating oil according to claim 1 wherein the. soap contains a constituent-iron the class consisting of ahalogen. sulfur and phosphorus. I

I 1'7. A lubricating oil according to claim 4 wherein the soap contains a constituent from the class consisting of a halogen, sulfur and phosphorus.

18. A mineral lubricating oil for internal combustion engines containing a small proportion low catalytic activity with a saponifiable organic acid, and a small proportion of an oil-soluble alkaline earth metal salt of a phenol sulfide.

19. A mineral lubricating oil for Diesel engines and the like comprising a minor proportion of an oil-soluble alkaline earth metal soap of a saponifiable organic acid, and a minor proportion of an oil-soluble alkaline earth metal salt small proportion of an oil-soluble alkaline earth metal soap of a saponifiable organic acid, and a small proportion of an oil-soluble alkaline earth metal salt of an alkyl phenol sulfide.

21. An oil according to claim 20 wherein the metal of the phenolate replaces the hydrogen of the hydroxyl group.

22. A mineral lubricating oil containing a minor proportion of an oil-soluble alkaline earth metal soap of a. saponiflable organic acid, and a minor proportion of an oil-soluble alkaline earth metal salt of hvdrox'y phenyl sulfur compounds where the metal replaces the hydrogen of the hydroxyl group.

23. A mineral lubricating oil containing a minor proportion of an oil-soluble alkaline earth metal soap of saponifiable organic acid and a minor proportion of an oil-soluble alkaline earth metal salt of a phenolic thio-ether compound.

24. An oil according to claim 19 wherein the 2,28L82d I of oil-soluble soap of an alkaline earth metal of soap of a saponifiable organic acid comprises soap of acids produced ,by the oxidation of .a petroleum fraction.

25. An oil according to claim 19 wherein the soap of a saponiflable organic acid comprises soap of acids produced by the oxidation of a highly 'paraflinic petroleum fraction.

26. An oil according to claim 10 wherein the 29. An oil according to claim 18 wherein the I soap is a calcium chloro-stearate.

30. An oil according to claim 18 wherein the soap is a calcium phenyl stearate.

31. An oil according to claim 19 wherein the soap is a chloro-stearate.

32. An oil according to claim 19 wherein the soap is a phenyl stearate.

33. A lubricating oil for severe service internal I combustion engines according to claim 23, wherein the metal constituents are alkaline earth metals selected from the group consisting of calcium, barium and magnesium.

ULRIC B. BRAY. 

